Essex District Attorney Jonathan Blodgett said the arrests have put a “major dent” in organized crime in Massachusetts.

Rossetti has been jailed on heroin trafficking charges since May. He pleaded not guilty, and his attorney challenged prosecutors’ claim that he is a mob boss. The new indictment accuses Rossetti of organizing a criminal network involved in extortion, drug trafficking, robberies, assaults and other crimes.

Darin Bufalino, of Winthrop, was one of three men arrested Wednesday.

A prosecutor said in court Thursday that Bufalino was a “soldier” working for Rossetti. Bufalino’s attorney said Bufalino works for a scrap metal company and is not a mobster.

Last year, authorities began investigating Joseph Giallanella, an alleged bookmaker and loan shark from North Andover, Attorney General Martha Coakley said. The investigation spread into organized crime activity across eastern Massachusetts.

“These individuals not only perpetrated threats of violence and vicious attacks in order to collect gaming debts, but also engaged in extensive drug trafficking,” Blodgett said.

During the investigation, authorities seized $1.3 million in cash associated with illegal gaming and loan sharking, $120,000 in drug money, more than a kilo of heroin and 200 pounds of marijuana.